The purpose of this research is to examine the role of social stimuli in coordinating reproductive functions in rodents. To attain this goal we specifically study the influence of male stimulation on female sexual maturation in mice and the influence of female stimulation on adult male reproductive functioning in hamsters. Urine from adult males accelerates the sexual maturation of female mice. This effect is due to a substance associated with the protein component of male urine. We propose to identify this pheromone more precisely and to determine its mode of reception by the female. The presence of adult female hamsters interacts with prolonged photoperiod to accelerate male sexual recrudescence. We have now shown that this effect can be induced by bedding material soiled by estrous females. Studies proposed will determine whether female stimulation alone, in the absence of increased photoperiod, will hasten reproductive recrudescence.